I am certain that the cruise units from 1970 on up all work the same. There is section in 1970 FSM for diagnosis and service. There is nothing in there about repairing the transducer. Wiring diagram should show the wiring for the brake pedal switch, the turn signal lever with the speed control switch.

One of the easy tests for the transducer, is to turn ign to ON or ACC, then pull the double connector off the transducer . . should here clicking noise if it is ok. No clicking, replace.

Your unit sounds just like the first one I put on my Satellite . . . looked great, etc . . .however, it would not pick up. I did the above test, and replaced the transducer, VOILA, now there is cruise control !! Good Luck . . .

Cheers,

Mark